Polyester elastomer resin composition

Abstract

To provide a polyester elastomer resin composition capable of being molded without foaming even at high processing temperatures while being a copolymer of PTMG.SOLUTION: There is provided a polyester elastomer resin composition which comprises a polyester elastomer (A) in which a hard segment composed of a polyester comprising an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent units and a soft segment comprising polytetramethylene ether glycol as a constituent unit are bonded, wherein 88 to 100 mol% of the aromatic dicarboxylic acid component is composed of terephthalic acid units and 0 to 12 mol% thereof is composed of isophthalic acid units, the aliphatic and / or alicyclic diol component comprises ethylene glycol units as the main component, 85 to 99 mol% of the total glycol component constituting the polyester elastomer (A) is composed of ethylene glycol units and 1 to 15 mol% of the total glycol component is composed of poly(tetramethylene ether glycol units, 0.01 to 1 pt.mass of a peroxide decomposer is contained based on 100 pts.mass of (A) and the melting point of (A) is 220 to 245°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyester elastomer resin composition that has excellent heat resistance, allows mass production of pellets without foaming during casting after polymerization of the polyester elastomer, and has excellent color. [Background technology]

[0002] Polyester elastomers are excellent in injection and extrusion moldability, and as a material with high mechanical strength, rubber-like properties such as elastic recovery, impact resistance, and flexibility, as well as excellent heat and cold resistance, they are used in a wide range of applications, including automotive parts, electrical and electronic parts, fibers, films, and sports parts.

[0003] Polyesters are used in automotive parts and electrical and electronic components due to their excellent heat resistance and mechanical properties. Copolymerizing polyester with polytetramethylene ether glycol (PTMG) as a soft segment can impart flexibility, making it promising for use as a polyester elastomer with excellent heat resistance (Patent Document 1). However, such elastomers have a high melting point, requiring high processing temperatures for molding. Molding at high processing temperatures can cause foaming, making it difficult to produce pellets from the polyester elastomer by casting, and further molding the resulting pellets can result in air bubbles being trapped in the products, resulting in problems with poor quality, such as poor heat resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 3270185 Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made to solve the above-mentioned problems of the conventional art, and an object of the present invention is to provide a polyester elastomer resin composition which is a polyester elastomer copolymerized with PTMG and has excellent flexibility, and which can be molded without foaming even at high processing temperatures. [Means for solving the problem]

[0006] As a result of extensive research to achieve the above object, the present inventors discovered that foaming in polyester elastomers copolymerized with PTMG during molding at high temperatures is caused by the generation of peroxides due to the decomposition of PTMG in the soft segment of the elastomer. They then discovered that the generation of peroxides can be effectively suppressed by adding a specific amount of a peroxide decomposer to the polyester elastomer, resulting in efficient production of high-quality pellets and products without foaming even at high processing temperatures, and that the timing of addition of the peroxide decomposer is also important, leading to the completion of the present invention.

[0007] That is, the present invention has the following features (1) to (7). (1) A polyester elastomer resin composition comprising a polyester elastomer (A) in which a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components and a soft segment made of a polytetramethylene ether glycol as constituent component are bonded, wherein the aromatic dicarboxylic acid component comprises 88 to 100 mol % of terephthalic acid units and 0 to 12 mol % of isophthalic acid units, the aliphatic and / or alicyclic diol component is mainly composed of ethylene glycol units, 85 to 99 mol % of all glycol components constituting the polyester elastomer (A) are composed of ethylene glycol units and 1 to 15 mol % of all glycol components are composed of polytetramethylene ether glycol units, a peroxide decomposer (B) is contained in an amount of 0.01 to 1 part by mass per 100 parts by mass of the polyester elastomer (A), and the polyester elastomer (A) has a melting point of 220°C to 245°C. (2) A polyester elastomer resin composition according to (1), characterized in that the amount of tetrahydrofuran (THF) generated when heated at 15°C above the melting point of the polyester resin composition for 60 minutes is 4000 ppm or less as measured by GC / FID. (3) The polyester elastomer resin composition according to (1), wherein the peroxide decomposer (B) is at least one selected from the group consisting of phosphonites, phosphites, and hindered amine stabilizers. (4) The polyester elastomer resin composition according to (1), wherein the polyester resin composition has a heat of fusion of 20 to 40 J / g. (5) The polyester elastomer resin composition according to (1), characterized in that the polyester resin composition has a durometer hardness type-D of 40 to 75 as measured in accordance with ISO 48-4:2018. (6) The polyester elastomer resin composition according to (1), wherein the Co-b value of the polyester elastomer resin composition is 10 or less. (7) A method for producing a polyester elastomer resin composition according to any one of (1) to (6), characterized in that the peroxide decomposer (B) is added after the polymerization reaction of the polyester elastomer (A) is completed and before casting. [Effects of the Invention]

[0008] Although the polyester elastomer resin composition of the present invention requires a high processing temperature due to its high melting point, the incorporation of a peroxide decomposer suppresses the generation of peroxides, and therefore molding processing can be performed without foaming, and good quality pellets and products can be efficiently produced. DETAILED DESCRIPTION OF THE INVENTION

[0009] The polyester elastomer resin composition of the present invention contains, as a main component, a polyester elastomer (A) having a polyester of a specific composition as a hard segment and PTMG as a soft segment, and is characterized in that a specific amount of a peroxide decomposer (B) is blended with the polyester elastomer (A), and the polyester elastomer (A) has a melting point of 220 to 245°C.

[0010] [Polyester elastomer (A)] The polyester elastomer (A) is composed of a hard segment made of a polyester containing an aromatic dicarboxylic acid component and an aliphatic and / or alicyclic diol component as constituent components, and a soft segment made of PTMG as a constituent component.

[0011] The main aromatic dicarboxylic acid constituting the polyester of the hard segment of the polyester elastomer (A) is terephthalic acid. The content of terephthalic acid units in the aromatic dicarboxylic acid component is 88 mol% or more, preferably 94 mol% or more, and may be 100 mol%. The dicarboxylic acid component other than terephthalic acid is isophthalic acid. Isophthalic acid can be used in a range that does not significantly lower the melting point of the polyester elastomer, and the content of isophthalic acid units is 12 mol% or less, preferably 6 mol% or less, and may be 0 mol% of the total acid components. If the amount of isophthalic acid is too high, satisfactory moldability (crystallinity) may not be obtained. When these dicarboxylic acids are used as raw materials for the polyester elastomer, they may be esters of the dicarboxylic acid. For example, terephthalic acid or dimethyl terephthalate can also be used as raw materials.

[0012] Ethylene glycol is used as the main component of the aliphatic and / or alicyclic diol constituting the polyester of the hard segment. The content of ethylene glycol units is 85 to 99 mol% of the total glycol components constituting the polyester elastomer (A). Therefore, in the present invention, the main component constituting the polyester of the hard segment is ethylene terephthalate units (units consisting of terephthalic acid and ethylene glycol). The content of ethylene glycol units is preferably 87 to 98 mol%, more preferably 90 to 95 mol%.

[0013] In addition, when an aromatic polyester suitable as the polyester constituting the hard segment of the polyester elastomer (A) is produced in advance and then copolymerized with the soft segment component, the aromatic polyester can be easily obtained according to a conventional polyester production method. In addition, such a polyester preferably has a number average molecular weight of 10,000 to 40,000.

[0014] PTMG is used as the aliphatic polyether constituting the soft segment of the polyester elastomer (A). The number average molecular weight of PTMG is preferably 500 to 4000, more preferably 700 to 3000, and even more preferably 800 to 2500. If the number average molecular weight is below the above range, it may be difficult to exhibit elastomeric properties. On the other hand, if the number average molecular weight exceeds the above range, compatibility with the hard segment component may decrease, making it difficult to copolymerize in a block form.

[0015] The copolymerization amount of the PTMG is 1 to 15 mol %, preferably 2 to 13 mol %, and more preferably 5 to 10 mol %, when the total amount of glycol components constituting the polyester elastomer (A) is 100 mol %.

[0016] The mass ratio of hard segments to soft segments in the polyester elastomer (A) is preferably 50:50 to 95:5, more preferably 53:47 to 89:11, even more preferably 60:40 to 76:24, and particularly preferably 66:34 to 73:27. If the hard segment content is low (PTMG content is high), satisfactory moldability (crystallinity) may not be achieved. Conversely, if the hard segment content is high (PTMG content is low), the glass transition temperature (Tg) may be accordingly high, and satisfactory impact resilience, flexibility, and low-temperature mechanical properties may not be achieved. Furthermore, the compatibility between the hard segment and soft segment components may decrease, making it difficult to copolymerize them into blocks.

[0017] The melting point of the polyester elastomer (A) is 220 to 245°C, preferably 225 to 240°C. If the melting point is below the above range, the moldability (crystallinity) may not be satisfactory. If the melting point is above the above range, the processing temperature becomes too high, and foaming during molding may not be sufficiently suppressed even if a peroxide decomposer (B) is added.

[0018] The polyester elastomer (A) can be produced by known methods (e.g., JP-A-10-182954, WO 2007 / 072748, etc.), such as a method of transesterifying a lower alcohol diester of a dicarboxylic acid, an excess amount of a low-molecular-weight glycol, and a soft segment component in the presence of a catalyst and then polycondensing the resulting reaction product, a method of esterifying a dicarboxylic acid, an excess amount of a glycol, and a soft segment component in the presence of a catalyst and then polycondensing the resulting reaction product, a method of preparing hard segments in advance, adding soft segment components to the hard segments, and randomizing them by transesterification, or a method of linking hard segments and soft segments with a chain linking agent.

[0019] [Peroxide decomposer (B)] The polyester elastomer resin composition of the present invention contains 0.01 to 1 part by mass, preferably 0.02 to 0.8 parts by mass, and more preferably 0.03 to 0.7 parts by mass of peroxide decomposer (B) per 100 parts by mass of polyester elastomer (A). The peroxide decomposer (B) is a compound capable of decomposing peroxides into alcohols and is different from a simple stabilizer. In the present invention, even if peroxides that cause foaming are generated during molding at high temperatures, they are decomposed by the peroxide decomposer. Therefore, foaming during molding is suppressed, and high-quality pellets and products can be efficiently produced. If the content of the peroxide decomposer is less than the above range, this effect is not fully exerted. Furthermore, if the content of the peroxide decomposer is greater than the above range, the effect is not further improved and, conversely, the color may be impaired.

[0020] The peroxide decomposer (B) is preferably a phosphonite (a compound having one carbon-phosphorus bond and two phosphorus-oxygen bonds, RP-(OR)2), a phosphite (a compound having three phosphorus-oxygen bonds, P-(OR)3), or a hindered amine stabilizer (HALS). In the chemical formulae of the phosphonite and phosphite, R represents a hydrocarbon group, which may be the same or different and may have a structure in which the groups are linked together. The hydrocarbon group may have a structure in which a substituent such as a hydroxyl group or a halogen group is linked to a hydrocarbon. From the viewpoint of the heat resistance of the peroxide decomposer itself, R preferably has an aromatic structure, an alicyclic structure, or a ring structure in which the rings are linked together. The peroxide decomposer (B) is more preferably at least one of a phosphonite and a phosphite, which have a significant effect of suppressing foaming during molding.

[0021] The timing of adding the peroxide decomposer (B) to the polyester elastomer resin composition of the present invention is preferably after the completion of the polymerization reaction of the polyester elastomer (A) and before casting to produce pellets, in order to fully exert the foaming-inhibiting effect of the peroxide decomposer (B). In this invention, "casting" refers to the process of removing the molten resin after the completion of polymerization from the reaction system in the form of strands, solidifying them, and cutting them into pellets. The reason for adding the peroxide decomposer (B) before casting is that peroxides, which cause foaming, are generated during the casting to produce pellets. However, adding the peroxide decomposer (B) before the completion of the polymerization reaction, even if it is before casting, will inhibit the polymerization reaction, preventing the above-mentioned effect of the peroxide decomposer (B) from being fully exerted.

[0022] The polyester elastomer resin composition of the present invention is not limited to those obtained by adding the peroxide decomposer (B) after the polymerization reaction of the polyester elastomer (A) is completed and before casting, but also includes those obtained by adding the peroxide decomposer (B) during compounding (kneading) with other additives after casting. In this case, foaming during the production of pellets from the polyester elastomer by casting cannot be suppressed, but foaming can be suppressed when the polyester elastomer resin composition obtained by compounding is further molded to produce a product. This prevents air bubbles from being mixed into the resulting product, and still achieves the effect of improving the heat resistance of the product.

[0023] [Other additives] In addition to the polyester elastomer (A) and peroxide decomposer (B), the polyester elastomer resin composition of the present invention can contain general-purpose antioxidants such as aromatic amines, hindered phenols, and sulfur-based antioxidants. These antioxidants may be used in combination of two or more. Examples of aromatic amine-based antioxidants include phenylnaphthylamine, 4,4'-dimethoxydiphenylamine, 4,4'-bis(α,α-dimethylbenzyl)diphenylamine, and 4-isopropoxydiphenylamine.

[0024] As the hindered phenol-based antioxidant, any general-purpose compound can be used, but those with a molecular weight of 500 or more, such as N,N'-hexamethylene-bis(3,5-di-t-butyl-4-hydroxyhydrocinnamic acid amide) and tetrakis[methylene-3(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane, are preferred because they are less likely to volatilize in a high-temperature atmosphere.

[0025] Examples of sulfur-based antioxidants include sulfur-containing compounds such as thioethers, dithioacid salts, mercaptobenzimidazoles, thiocarbanilides, and thiodipropionates. Specific examples include dilauryl thiodipropionate, distearyl thiodipropionate, didodecyl thiodipropionate, ditetradecyl thiodipropionate, dioctadecyl thiodipropionate, pentaerythritol tetrakis(3-dodecylthiopropionate), thiobis(N-phenyl-β-naphthylamine), 2-mercaptobenzothiazole, 2-mercaptobenzimidazole, tetramethylthiuram monosulfide, tetramethylthiuram disulfide, nickel dibutyldithiocarbamate, nickel isopropyl xanthate, and trilauryl trithiophosphite. Thioether-based antioxidants, which have a thioether structure, are particularly suitable because they accept oxygen from oxidized substances and reduce them.

[0026] When the above antioxidants are blended, the blending amount is preferably 0.01 to 3 parts by mass, more preferably 0.05 to 2 parts by mass, and even more preferably 0.1 to 1 part by mass, per 100 parts by mass of the polyester elastomer (A).

[0027] The composition and composition ratio of the polyester elastomer resin composition used in the present invention can be determined by dissolving a sample in a solvent such as deuterated chloroform and measuring the composition. 1 It can also be calculated from the proton integral ratio in H-NMR.

[0028] Furthermore, if the polyester elastomer resin composition of the present invention requires weather resistance, an ultraviolet absorber and / or a hindered amine compound can be blended. For example, benzophenone-based, benzotriazole-based, triazole-based, nickel-based, or salicylic acid-based light stabilizers can be used. The blending amount is preferably 0.1% to 5% or less based on the mass of the resin composition.

[0029] The polyester elastomer resin composition of the present invention may contain other additives, such as resins other than those described above, inorganic fillers, stabilizers, and antioxidants, provided that the features of the present invention are not impaired. Other additives may also be added, such as coloring pigments, inorganic or organic fillers, coupling agents, tackiness improvers, stabilizers such as quenchers and metal deactivators, and flame retardants. The total amount of these various additives is preferably 20 parts by mass or less, and more preferably 10 parts by mass or less, per 100 parts by mass of the polyester elastomer (A).

[0030] The polyester elastomer resin composition of the present invention preferably has a heat of fusion of 20 to 40 J / g, more preferably 25 to 40 J / g. If the heat of fusion is less than 20 J / g, it may not be possible to obtain a composition that satisfies the moldability (crystallinity) function. Furthermore, if the heat of fusion is less than 25 J / g, blocking (sticking of pellets together) may occur during pelletization.

[0031] The polyester elastomer resin composition of the present invention preferably has an amount of tetrahydrofuran (THF) measured by GC / FID when heated at 15°C above its melting point for 60 minutes of 4000 ppm or less, more preferably 3600 ppm or less, and even more preferably 3200 ppm or less. Since THF is a decomposition product of PTMG, if the amount of THF exceeds the upper limit, foaming is likely to occur during molding.

[0032] In order to achieve long-term durability (heat aging resistance, water resistance, etc.), the polyester elastomer resin composition of the present invention preferably has a reduced viscosity of 0.7 dL / g or more, more preferably 0.8 dL / g or more, and even more preferably 0.9 dL / g or more. If the reduced viscosity is below the lower limit, the molecular weight is small, and the polyester elastomer resin composition may not have a satisfactory long-term durability.

[0033] From the viewpoint of the appearance of molded articles, the polyester elastomer resin composition of the present invention preferably has a Co-b value of 10 or less, more preferably 7.5 or less, and even more preferably 6.0 or less. If Co-b exceeds the upper limit, the prepared pellets will turn yellow, significantly impairing the appearance of the molded article, and therefore, depending on the application, a satisfactory product may not be obtained.

[0034] The polyester elastomer resin composition of the present invention can be produced by melt-kneading the components using a conventional thermoplastic resin mixer, such as a single-screw or twin-screw melt-kneader or a kneader-type heater, followed by pelletizing the components in a granulation step. [Example]

[0035] The following examples are provided to demonstrate the effects of the present invention, but the present invention is not limited to these examples. The evaluation of each measurement value was carried out by the following methods.

[0036] [Melting point] Using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc., 5 mg of the measurement sample was placed in an aluminum pan, the lid was pressed down to seal it, and the sample was held at 260°C for 5 minutes to completely melt the sample, then rapidly cooled with liquid nitrogen, and then measured from -150°C to 260°C at a heating rate of 20°C / min. The endothermic peak temperature of the obtained thermogram curve was taken as the melting point.

[0037] [Reduced viscosity] 0.05 g of the polyester elastomer was dissolved in 25 mL of a mixed solvent (phenol / tetrachloroethane=60 / 40), and the reduced viscosity was measured at 30° C. using an Ubbelohde viscometer.

[0038] [Acid value] 200 mg of thoroughly dried polyester elastomer was dissolved in 10 mL of hot benzyl alcohol, and the resulting solution was cooled. After that, 10 mL of chloroform and phenol red were added, and the acid value (eq / ton) was determined by the dissolution titration method in which the solution was titrated with a 1 / 25 N potassium hydroxide solution (a solution of KOH in methanol).

[0039] The components used in the examples are as follows:

[0040] [Polyester elastomer (A)] (Polyester elastomer (A-1): DMI content 5 mol%, PTMG content 7 mol%) A reactor was charged with 48.1 parts by mass of dimethyl terephthalate (DMT, manufactured by SK Petrochemical), 2.5 parts by mass of dimethyl isophthalate (DMI, manufactured by TUOSHI CEMICAL), 31.2 parts by mass of ethylene glycol (EG, manufactured by Nippon Shokubai), and 18.2 parts by mass of polytetramethylene ether glycol (PTMG1000, manufactured by BASF, molecular weight 1000 g / mol). Additionally, 0.05 parts by mass of antimony trioxide (SbO, manufactured by Nippon Seiko) and 0.05 parts by mass of zinc acetate dihydrate (ZnOAc, manufactured by Nacalai Tesque) were charged to the reactor as catalysts per 100 parts by mass of the polymer to be purified. The temperature was raised from room temperature to 220°C over 130 minutes, and a transesterification reaction was carried out. The pressure inside the reactor was then gradually reduced and the temperature was further raised to 245°C and 1 Torr or less over 70 minutes, and an initial condensation reaction was carried out. The polymerization reaction was then carried out at 250°C under a pressure of 1 Torr or less for 60 minutes. After the polymerization reaction was completed, the polymer was cast and pelletized to obtain a polyester elastomer (A-1) with a hard segment / soft segment ratio of 69 / 31 (mass%). The melting point of this polyester elastomer (A-1) was 230°C, the reduced viscosity was 1.14 dl / g, and the acid value was 21 eq / ton.

[0041] (Polyester elastomer resin composition (A-2): DMI content 5 mol%, PTMG content 7 mol%, peroxide decomposer (B-1) content 0.07 parts by mass) In the production method for polyester elastomer (A-1), after the polymerization reaction was completed, peroxide decomposer (B-1) ADK STAB PEP-36 (phosphorus-based antioxidant (phosphite), manufactured by ADEKA) was added to the reactor at a ratio of 0.07 parts by mass per 100 parts by mass of purified polymer and stirred. After stirring, the polymer was cast and removed as pellets to obtain polyester elastomer resin composition (A-2) with a hard segment / soft segment ratio of 69 / 31 (mass%). This polyester elastomer resin composition (A-2) had a melting point of 230°C, a reduced viscosity of 1.15 dl / g, and an acid value of 23 eq / ton.

[0042] (Polyester elastomer resin composition (A-3): DMI content 5 mol%, PTMG content 7 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) In the production method of polyester elastomer (A-1), after the polymerization reaction was completed, peroxide decomposer (B-1) was added to the reactor at a ratio of 0.15 parts by mass per 100 parts by mass of purified polymer and stirred. After stirring, the polymer was cast and removed as pellets to obtain polyester elastomer resin composition (A-3) with a hard segment / soft segment ratio of 69 / 31 (mass%). This polyester elastomer resin composition (A-3) had a melting point of 230°C, a reduced viscosity of 1.15 dl / g, and an acid value of 23 eq / ton.

[0043] (Polyester elastomer resin composition (A-4): DMI content 5 mol%, PTMG content 7 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) In the production method of polyester elastomer (A-1), after the polymerization reaction was completed, peroxide decomposer (B-1) was added to the reactor at a ratio of 0.50 parts by mass per 100 parts by mass of purified polymer and stirred. After stirring, the polymer was cast and removed as pellets to obtain polyester elastomer resin composition (A-4) with a hard segment / soft segment ratio of 69 / 31 (mass%). This polyester elastomer resin composition (A-4) had a melting point of 230°C, a reduced viscosity of 1.15 dl / g, and an acid value of 24 eq / ton.

[0044] (Polyester elastomer resin composition (A-5): DMI content 5 mol%, PTMG content 10 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) In the production method for polyester elastomer resin composition (A-2), 44.7 parts by mass of DMT, 2.4 parts by mass of DMI, 28.6 parts by mass of EG, and 24.3 parts by mass of PTMG1000 were charged into a reactor. The remaining production methods were the same as those for polyester elastomer resin composition (A-2), and a polyester elastomer resin composition (A-5) with a hard segment / soft segment ratio of 60 / 40 (mass%) was obtained. This polyester elastomer resin composition (A-5) had a melting point of 221°C, a reduced viscosity of 1.24 dl / g, and an acid value of 20 eq / ton.

[0045] (Polyester elastomer resin composition (A-6): DMI content 5 mol%, PTMG content 2 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) In the production method for polyester elastomer resin composition (A-2), 54.7 parts by mass of DMT, 2.9 parts by mass of DMI, 36.5 parts by mass of EG, and 5.9 parts by mass of PTMG1000 were charged into a reactor. The remaining production methods were the same as those for polyester elastomer resin composition (A-2), and a polyester elastomer resin composition (A-6) with a hard segment / soft segment ratio of 89 / 11 (mass%) was obtained. This polyester elastomer resin composition (A-6) had a melting point of 242°C, a reduced viscosity of 0.85 dl / g, and an acid value of 29 eq / ton.

[0046] (Polyester elastomer resin composition (A-7): DMI content 0 mol%, PTMG content 7 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) The same manufacturing method as for polyester elastomer resin composition (A-2) was used, but with the following changes: DMT (50.6 parts by mass), DMI (0 parts by mass), EG (31.2 parts by mass), and PTMG1000 (18.2 parts by mass) were added to a reactor. The remaining manufacturing procedures were the same as for polyester elastomer resin composition (A-2), and a polyester elastomer resin composition (A-7) with a hard segment / soft segment ratio of 69 / 31 (mass%) was obtained. This polyester elastomer resin composition (A-7) had a melting point of 238°C, a reduced viscosity of 1.10 dl / g, and an acid value of 23 eq / ton.

[0047] (Polyester elastomer resin composition (A-8): DMI content 0 mol%, PTMG content 13 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) In the same manner as in the production of polyester elastomer resin composition (A-2), the DMT was changed to 44.1 parts by mass, and the DMI, 0 parts by mass, EG to 26.4 parts by mass, and PTMG1000 to 29.5 parts by mass were charged into a reactor. The remaining production procedures were the same as in the production of polyester elastomer resin composition (A-2), and a polyester elastomer resin composition (A-8) with a hard segment / soft segment ratio of 53 / 47 (mass%) was obtained. This polyester elastomer resin composition (A-8) had a melting point of 222°C, a reduced viscosity of 1.27 dl / g, and an acid value of 19 eq / ton.

[0048] (Polyester elastomer resin composition (A-9): DMI content 10 mol%, PTMG content 2 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) In the production method for polyester elastomer resin composition (A-2), 51.8 parts by mass of DMT, 5.8 parts by mass of DMI, 36.5 parts by mass of EG, and 5.9 parts by mass of PTMG1000 were charged into a reactor. The remaining production methods were the same as those for polyester elastomer resin composition (A-2), and a polyester elastomer resin composition (A-9) with a hard segment / soft segment ratio of 89 / 11 (mass%) was obtained. This polyester elastomer resin composition (A-9) had a melting point of 233°C, a reduced viscosity of 0.85 dl / g, and an acid value of 29 eq / ton.

[0049] (Polyester elastomer resin composition (A-10): DMI content 20 mol%, PTMG content 7 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) In the production method for polyester elastomer resin composition (A-2), 40.5 parts by mass of DMT, 10.1 parts by mass of DMI, 31.2 parts by mass of EG, and 18.2 parts by mass of PTMG1000 were charged into a reactor. The remaining production procedures were the same as for polyester elastomer resin composition (A-2), and a polyester elastomer resin composition (A-10) with a hard segment / soft segment ratio of 69 / 31 (mass%) was obtained. This polyester elastomer resin composition (A-10) had a melting point of 193°C, a reduced viscosity of 1.15 dl / g, and an acid value of 23 eq / ton.

[0050] (Polyester elastomer resin composition (A-11): DMI content 5 mol%, PTMG content 25 mol%, peroxide decomposer (B-1) content 0.15 parts by mass) The same method as for producing polyester elastomer resin composition (A-2) was used, but instead of 33.4 parts by mass of DMT, 1.8 parts by mass of DMI, 19.6 parts by mass of EG, and 45.2 parts by mass of PTMG1000 were charged into a reactor. The remaining production procedures were the same as for polyester elastomer resin composition (A-2), and a polyester elastomer resin composition (A-11) with a hard segment / soft segment ratio of 34 / 66 (mass%) was obtained. This polyester elastomer resin composition (A-11) had a melting point of 183°C, a reduced viscosity of 1.30 dl / g, and an acid value of 17 eq / ton.

[0051] (Polyester elastomer (A-12): DMI content 0 mol%, PTMG content 7 mol%) In the production method for polyester elastomer (A-1), the DMT was changed to 50.6 parts by mass, and the DMI, DMI, EG, and PTMG1000 were added to 0 parts by mass, 31.2 parts by mass, and 18.2 parts by mass, respectively, in a reactor. The remaining production methods were the same as those for polyester elastomer (A-1), and polyester elastomer (A-12) with a hard segment / soft segment ratio of 69 / 31 (mass%) was obtained. This polyester elastomer (A-12) had a melting point of 239°C, a reduced viscosity of 1.10 dl / g, and an acid value of 23 eq / ton.

[0052] (Polyester elastomer resin composition (A-13): DMI content 5 mol%, PTMG content 7 mol%, peroxide decomposer (B-2) content 0.15 parts by mass) In the production method for polyester elastomer (A-1), after the polymerization reaction was completed, peroxide decomposer (B-2) HOSTANOX P-EPQ (phosphorous antioxidant (phosphonite), manufactured by Clariant Japan) was added to the reactor at a ratio of 0.15 parts by mass per 100 parts by mass of purified polymer and stirred. After stirring, the polymer was cast and removed as pellets, yielding polyester elastomer resin composition (A-13) with a hard segment / soft segment ratio of 69 / 31 (mass%). This polyester elastomer resin composition (A-13) had a melting point of 230°C, a reduced viscosity of 1.15 dl / g, and an acid value of 23 eq / ton.

[0053] (Polyester elastomer resin composition (A-14): DMI content 5 mol%, PTMG content 7 mol%, peroxide decomposer (B-3) content 0.15 parts by mass) In the production method for polyester elastomer (A-1), after the polymerization reaction was completed, peroxide decomposer (B-3) Chimassorb 944 FDL (hindered amine-based HALS, manufactured by BASF Japan) was added to the reactor at a ratio of 0.15 parts by mass per 100 parts by mass of purified polymer and stirred. After stirring, the polymer was cast and removed as pellets to obtain polyester elastomer resin composition (A-14) with a hard segment / soft segment ratio of 69 / 31 (mass%). This polyester elastomer resin composition (A-14) had a melting point of 230°C, a reduced viscosity of 1.15 dl / g, and an acid value of 23 eq / ton.

[0054] (Polyester elastomer resin composition (A-15): DMI content 5 mol%, PTMG content 7 mol%, peroxide decomposer (B-1) content 0.005 parts by mass) In the production method of polyester elastomer (A-1), after the polymerization reaction was completed, peroxide decomposer (B-1) was added to the reactor at a ratio of 0.005 parts by mass per 100 parts by mass of purified polymer and stirred. After stirring, the polymer was cast and removed as pellets to obtain polyester elastomer resin composition (A-15) with a hard segment / soft segment ratio of 69 / 31 (mass%). This polyester elastomer resin composition (A-15) had a melting point of 230°C, a reduced viscosity of 1.15 dl / g, and an acid value of 23 eq / ton.

[0055] (Polyester elastomer resin composition (A-16): DMI content 5 mol%, PTMG content 7 mol%, peroxide decomposer (B-1) content 1.5 parts by mass) In the production method of polyester elastomer (A-1), after the polymerization reaction was completed, peroxide decomposer (B-1) was added to the reactor at a ratio of 1.5 parts by mass per 100 parts by mass of purified polymer and stirred. After stirring, the polymer was cast and removed as pellets to obtain polyester elastomer resin composition (A-16) with a hard segment / soft segment ratio of 69 / 31 (mass%). This polyester elastomer resin composition (A-16) had a melting point of 230°C, a reduced viscosity of 1.15 dl / g, and an acid value of 23 eq / ton.

[0056] The compositions and physical properties of the polyester elastomers (resin compositions) (A-1) to (A-16) are shown in Table 1. The compositions in mol % in Table 1 are values ​​calculated from the ratio of raw materials charged and the molecular weight of each raw material.

[0057] [Table 1]

[0058] [Peroxide decomposer (B)] (B-1) Adekastab PEP-36 (phosphorus antioxidant (phosphite), manufactured by ADEKA) (B-2) HOSTANOX P-EPQ (phosphorous antioxidant (phosphonite), manufactured by Clariant Japan) (B-3) Chimassorb 944 FDL (hindered amine HALS, manufactured by BASF Japan)

[0059] Examples 1 to 5, Comparative Examples 2 and 3 According to the compositions and ratios shown in Table 2, 100 parts by mass of pellets of polyester elastomer (A-1) and peroxide decomposer (B) were kneaded and compounded in a twin-screw extruder to obtain pellets of polyester elastomer resin compositions of Examples 1 to 5 and Comparative Examples 2 and 3. Examples 6 to 15, Comparative Examples 4, 5, 7, and 8 In Examples 6 to 15 and Comparative Examples 4, 5, 7 and 8, pellets of the polyester elastomer resin composition to which the peroxide decomposer (B) had already been added before casting after the completion of the polymerization reaction were used as they were. Comparative Examples 1 and 6 In Comparative Examples 1 and 6, pellets of polyester elastomers (A-1) and (A-12), respectively, were used as they were. The pellets of these polyester elastomer resin compositions were used to carry out the following evaluations.

[0060] [Melting point] Using a differential scanning calorimeter "DSC220" manufactured by Seiko Instruments Inc., 5 mg of the measurement sample was placed in an aluminum pan, the lid was pressed down to seal it, and the sample was held at 260°C for 5 minutes to completely melt the sample, then rapidly cooled with liquid nitrogen, and then measured from -150°C to 260°C at a heating rate of 20°C / min. The endothermic peak temperature of the obtained thermogram curve was taken as the melting point.

[0061] [THF amount] 0.5 g of the polyester elastomer resin composition was heated at 15°C above the melting point for 60 minutes using a TE-2 (Gestell Corporation), and the collected liquid was then subjected to GC / FID gas chromatography to quantify the THF content.

[0062] [Polymerization mass productivity] After the polymerization of the polyester elastomer was completed, the polymerization mass productivity was evaluated based on whether or not sampling was possible during casting to produce pellets, according to the following criteria: If the strand foamed during casting, making sampling impossible due to foam inclusions, the polymerization mass productivity was evaluated as poor; conversely, if there was no foaming or only a small amount of foaming and sampling was consistently possible, the polymerization mass productivity was evaluated as excellent. No foaming of strands, allowing sampling: Excellent Strands are slightly trapped by bubbles, but sampling is possible: Yes Sampling is impossible due to excessive foaming of strands: Not possible

[0063] [Heat resistance (suppression of foaming during extrusion sheet production)] Pellets of the polyester elastomer resin composition were dried under reduced pressure at 120°C for 8 hours and then extruded into a sheet using a 30φ single-screw extruder at a cylinder temperature of 15°C higher than the melting point of the polyester elastomer resin composition. Heat resistance was evaluated based on whether foaming occurred and it was impossible to secure a sheet, according to the following criteria. If foaming occurred during extrusion molding and it was impossible to secure a sheet, the heat resistance was evaluated as poor. Conversely, if there was no foaming or only a small amount of foaming and it was possible to consistently secure a sheet, the heat resistance was evaluated as excellent. No foaming during extrusion molding, no bubbles in the sheet: Excellent No foaming during extrusion, but bubbles in the sheet: OK Severe foaming during extrusion molding makes it impossible to secure a sheet: Unavailable

[0064] [Heat of fusion] Using a differential scanning calorimeter "DSC220" manufactured by Seiko Electronics Co., Ltd., 5 mg of the measurement sample was placed in an aluminum pan, the lid was pressed down to seal it, and the sample was held at 260°C for 5 minutes to completely melt the sample, then rapidly cooled with liquid nitrogen, and then measured from -150°C to 260°C at a heating rate of 20°C / min. From the obtained thermogram curve, the endothermic peak area was taken as the heat of fusion.

[0065] [blocking] The polyester elastomer resin composition was kneaded and pelletized in a twin-screw extruder, and then allowed to stand at room temperature for 30 minutes. After standing, the presence or absence of adhesion between the pellets was evaluated according to the following criteria. The pellet shape is uniform and there is no adhesion of pellets: Excellent The pellet shape is uniform, but there is some adhesion of the pellets: Possible The pellet shape is uneven and the pellets are stuck together: Unacceptable

[0066] [Durometer hardness (type-D)] Durometer hardness was measured in a 23°C environment in accordance with the test method described in ISO 48-4. The test specimens used were injection-molded products (100mm square test specimens: width 100mm, length 100mm, thickness 2.0mm) made in an injection molding machine with a cylinder temperature 15°C higher than the melting point of the polyester elastomer resin composition and a mold temperature of 100°C. Three 100mm square test specimens were stacked on top of each other, and a needle tip was dropped onto them. The value 15 seconds after contact between the test specimen and the needle tip was read to measure durometer hardness (type-D).

[0067] [Color difference] The Co-b value of the polyester elastomer resin composition was measured using an automatic color difference meter (manufactured by Toyorika Kogyo Co., Ltd.) The larger the Co-b value, the greater the yellowness.

[0068] Table 2 shows the compositions and evaluation results of the polyester elastomer resin compositions of Examples 1 to 15 and Comparative Examples 1 to 8.

[0069] [Table 2]

[0070] As is clear from the results in Table 2, the polyester elastomer resin compositions of Examples 1 to 15, which satisfy the requirements of the present invention, contain an appropriate amount of peroxide decomposer (B) to suppress peroxide generation. This reduces the amount of THF, which is the direct cause of foaming. Therefore, foaming does not occur during extrusion molding, or the resulting sheets are bubble-free and have excellent heat resistance. In particular, Examples 9 and 12 have a low melting point due to the adjustment of the DMI and PTMG1000 contents, and the corresponding low processing temperature results in a lower amount of THF generation compared to other Examples. In Examples 6 to 15, the peroxide decomposer (B) was added after the completion of the polyester elastomer (A) polymerization reaction before casting, preventing strand foaming during casting during pellet production. Therefore, the compositions were also excellent in terms of polymerization productivity. Furthermore, Examples 9 and 12 had a high PTMG1000 content, resulting in a low durometer hardness (type-D) and excellent flexibility.

[0071] On the other hand, in Comparative Examples 1 and 6, since the peroxide decomposer (B) was not added, a large amount of THF, which is the direct cause of foaming, was generated, resulting in severe foaming during extrusion molding. Furthermore, in Comparative Example 6, whose melting point exceeded 235°C, severe foaming occurred during casting in pellet production, making sampling impossible. In Comparative Example 2, the amount of peroxide decomposer (B) added was too small, resulting in a large amount of THF generation and severe foaming during extrusion molding. In Comparative Example 3, the amount of peroxide decomposer (B) added was too large, resulting in a small amount of THF generation and no foaming during extrusion molding, but a high Co-b value and poor color. In Comparative Example 7, the amount of peroxide decomposer (B) added was too small, resulting in a large amount of THF generation and severe foaming during extrusion molding. In Comparative Example 8, the amount of peroxide decomposer (B) added was too large, resulting in a small amount of THF generation and no foaming during casting or extrusion molding, but a high Co-b value and poor color.

[0072] In Comparative Examples 4 and 5, the melting point was lower than 220°C by adjusting the DMI content and the PTMG1000 content. Although the amount of THF generated was small due to the low molding processing temperature, the heat of fusion was small, causing significant blocking and making it difficult to form uniform pellets. [Industrial Applicability]

[0073] The polyester elastomer resin composition of the present invention can be molded at high processing temperatures while copolymerizing PTMG, and high-quality pellets and products can be efficiently produced. Therefore, the polyester elastomer resin composition of the present invention can be molded into various molded articles by injection molding, extrusion molding, transfer molding, blow molding, etc., and can be used in a wide range of applications, such as automotive parts, electrical and electronic parts, fibers, films, and sports parts.

Claims

1. 1. A polyester elastomer resin composition comprising a polyester elastomer (A) in which a hard segment made of a polyester having an aromatic dicarboxylic acid and an aliphatic and / or alicyclic diol as constituent components and a soft segment made of polytetramethylene ether glycol as a constituent component are bonded, wherein the aromatic dicarboxylic acid component comprises 88 to 100 mol % of terephthalic acid units and 0 to 12 mol % of isophthalic acid units, the aliphatic and / or alicyclic diol component is primarily composed of ethylene glycol units, 85 to 99 mol % of all glycol components constituting the polyester elastomer (A) are composed of ethylene glycol units and 1 to 15 mol % of all glycol components are composed of polytetramethylene ether glycol units, 0.01 to 1 part by mass of a peroxide decomposer (B) is contained per 100 parts by mass of the polyester elastomer (A), and the polyester elastomer (A) has a melting point of 220°C to 245°C.

2. 2. The polyester elastomer resin composition according to claim 1, wherein the amount of tetrahydrofuran (THF) generated when heated at a temperature 15°C higher than the melting point of the polyester resin composition for 60 minutes is 4000 ppm or less as measured by a GC / FID method.

3. 2. The polyester elastomer resin composition according to claim 1, wherein the peroxide decomposer (B) is at least one member selected from the group consisting of phosphonites, phosphites, and hindered amine stabilizers.

4. 2. The polyester elastomer resin composition according to claim 1, wherein the polyester resin composition has a heat of fusion of 20 to 40 J / g.

5. The polyester elastomer resin composition according to claim 1, characterized in that the polyester resin composition has a durometer hardness type-D of 40 to 75 measured in accordance with ISO 48-4:2018.

6. 2. The polyester elastomer resin composition according to claim 1, wherein the polyester elastomer resin composition has a Co-b value of 10 or less.

7. 7. The method for producing a polyester elastomer resin composition according to claim 1, wherein the peroxide decomposer (B) is added after the polymerization reaction of the polyester elastomer (A) is completed and before casting.

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